1. Field of the Invention
The present invention relates to valve devices, and particularly to a valve device of an injection molding device for manufacturing a foil decorated molding.
2. Description of Related Art
Conventionally, various kinds of methods for manufacturing a foil decorated molding, which is molded by an injection molding process and has a transfer layer removed from a substrate foil of a transfer foil and placed on the surface of the molding after the transfer foil is inserted into cavities in an injection mold, have been known in the art. Since the use of the method requires an alignment of the transfer foil along a cavity-forming face of the mold, the transfer foil is preheated before the injection molding process so as to be easily aligned along the cavity-forming face of the mold where the cavity-forming face thereof is greatly recessed or projected from a parting face of the mold.
A traditional injection molding method includes transferring a heater between the male mold and the female mold to heat the foil before matching the molds, and removing the heater after the foil is heated. However, because of the need for the heater and the space it occupies, cost and volume of the injection mold is increased. A new method is used for elongating the foil between the male and female mold by exhausting air from a cavity via the female mold and pressurizing the foil by inputting thermal medium to cause the foil to cling to an inner surface of the cavity of the female mold. However, in this method, the thermal medium cannot be controlled.
What is needed is to provide a valve device for controlling supply of a thermal medium to an injection molding device.